Dear nThank you so very for your quick reply. nWe believe the chassis surrounding CPUs and heatsinks should navigate the air to move through the congested regions. nFollowing your message, I checked the contour of air volume fraction for the 1st time... nAnd it looks like air does move around heatsinks and air faction exceeds 30 % which totally contradicts with my previous results obtained by simply creating a point near neat heatsink and setting a probe under expressions.nAttached, please see the bottom image for the top contour located in the middle of upper heatsinks. nPlease kindly let me know how I should reason this contradiction and how to fix it. nnBest Regards,nNatn